This invention relates to burner assemblies for radiant tube heaters and, in particular, pressure sensors for use with such burner assemblies.
A known type of radiant heater for heating the interior of buildings and other areas is a so-called radiant tube heater which has a relatively long, radiant tube made of a suitable metal and adapted to enclose an elongate flame projected from a burner head. This heater includes a combustion air blower, a burner nozzle connected to a combustible gas supply through a gas valve unit, and a burner head connected to the nozzle. The nozzle and head are positioned in a combustion air duct section forming a passage for combustion air and the outlet of the blower is attached to an inlet end of this duct section so that the blower is able to direct combustion air through the duct section. The burner head which in an exemplary embodiment is arranged centrally in the air duct section, creates an annular passageway between itself and the air duct section. Combustible gas, such as natural gas, is delivered to the radiant heater through a gas valve governor which is connected by a line to the burner nozzle. Combustion air enters the burner head through vents or ports in the side wall of an inlet portion of the head and then mixes with the fuel, thereby producing a gas/air mixture which can exit through a perforated ceramic tile mounted in a downstream end of the head. The mixture is ignited by a suitable electrode resulting in a long laminer flame extending down the radiant tube.
One exemplary form of radiant tube heater is described and illustrated in co-pending U.S. patent application Ser. No. 11/831,130 filed Jul. 31, 2007 and the disclosure and drawings of this co-pending application are incorporated herein by reference. This radiant tube heater in addition to including the aforementioned features, employs a tubular arrangement that includes an air duct portion forming a combustion air passage and a radiant tube portion which is heated. An airflow restricting plate is mounted in the air duct portion and extends circumferentially around the burner head. This plate increases the flow of pressurized combustion air through the openings formed in the inlet portion of the burner head but also allows a substantial portion of the combustion air to flow downstream between the wider outlet portion of the head and the air duct portion.
The blower for the aforementioned radiant tube heater has a blower housing with a relatively straight, outlet section. Mounted on an outer wall of this outlet section are two pressure switches in the form of pitot tubes of standard construction. These switches are provided to ensure that the blower is in operation and is providing sufficient combustion air to the burner head when the mixture of combustion air and gas is ignited. The heater is constructed so as not to operate unless sufficient combustion air is being provided to the heater.
There is disclosed herein a pitot tube assembly for a radiant tube heater having a blower for providing combustion air to a burner assembly, this pitot tube assembly being constructed to provide a more accurate reading of static pressure when the tube heater is in use.